TM 55-1510-222-10 hopping/master)  position,  operationally  this  position  is identical to the FH position, except that it is a guarded, pull and turn switch position. (3) PRESET  Switch.    The  RT  PRESET switch is used to select specific predetermined operating conditions within the RT.  The switch is an eight position switch  whose  function  is  actually  two-fold.    In  a  normal single channel mode, (SC on the MODE switch), either manual    or    preset    frequencies    are    selected.        In    a frequency  hopping  mode  (FH  or  FH-M  on  the  MODE switch) frequency hopping nets are selected.  The switch is    also    used    in    single    channel    loading    of    preset frequencies.  The switch positions are indicated by MAN 1, 2, 3, 4, 5, 6 and CUE.  The CUE frequency can serve as a special signaling frequency in the FH modes, or as a seventh preset in single channel operation. The  MAN  (manual)  position  is  used  in  the  single channel mode to select any operating frequency, within the prescribed band, in 25 kHz increments.  Frequencies are entered directly by the keyboard.  Offsets of 5 or 10   kHz   may   be   applied   to   any   selected   frequency. Offsets applied to manually selected frequencies will be retained until a new frequency is selected or until offsets are cancelled.  Retention of offsets to manually selected frequency  will  be  in  effect  even  through  the  PRESET switch  is  moved  from  MAN  to  a  preset  frequency  and returned to MAN.  The MAN position is invalid for other positions  of  the  MODE  switch  (FH  or  FH-M)  and  an indication of "cold" will be in evidence on the display. The   CUE   frequency   can   serve   as   a   seventh preset   in   single   channel   operation   or   as   a   special signaling   frequency   in   the   FH   modes.      In   the   single channel  (SC)  mode,  preset  frequencies  are  selected  or loaded.      Frequency   selection   occurs   if   the   function switch  is  in  an  operational  position;  and  preset  loading occurs if the function switch is in the LD (load) position. The  display  will  indicate  the  preset  frequency  selected, providing  a  frequency  had  been  loaded  previously.    If frequency   data   had   not   been   loaded   in   the   preset position,   or   if   it   had   been   zeroized,   the   display   will indicate FILL, and the position number.  Offset of  5 or  10  kHz  may  be  applied  to  any  preset  and  will  be retained,   even   when   switching   between   presets,   until cancelled.  In the FH or FH-M mode, frequency hopping nets are selected according to predetermined preloading data.    It  is  not  necessary  to  use  the  PRESET  switch when   loading   FH   parameters;   however,   it   is   when selecting  particular  nets.    When  a  FH  net  is  selected, the   display   will   indicate   FH   followed   by   a   number corresponding   to   the   valid   FH   data   which   had   been loaded previously.  If valid data is not available for the net selected, the display will indicate FILLn (n = preset number). The  CUE  position  is  a  special  signaling  channel used by a non-ECCM radio to signal, or CUE, an ECCM radio.        The    CUE    channel    in    single    channel    (SC) operation  is,  in  effect  a  seventh  preset.    In  a  typical ECCM   CUE   operation,   a   radio   operator   with   a   non- ECCM  radio  attempting  a  contact  within  an  ECCM  net would place this switch to CUE and key the transmitter. The ECC'M radio provides an audible tone and a visual indication   that   contact   is   desired.      The   display   will indicate  CUE  for  a  period  of  7  seconds  and  a  tone  will be  apparent  for  2  seconds,  each  time  the  non-ECCM radio is keyed.  The non-ECCM radio must be keyed for at  least  4  seconds  to  ensure  reception  by  the  ECCM radio.    The  ECCM  radio  would  then  be  switched  to  the single    channel    CUE    or    some    other    pre-determined frequency to establish contact.  The CUE channel is an invalid   position   in   the   FIH   mode   and   the   radio   will operate in SC mode. (4) VOL   Control.      'The   VOL   (volume) control   is   a   potentiometer   which   serves   to   vary   the receiver volume.  The volume control is used to adjust receiver volume to a comfortable level. (5) Display.    The  display  is  a  five  digit, seven   segment   LCD   readout.      The   display   will   be illuminated  continuously  and  the  information  presented will  be  a  function  of  other  switch  settings  or  keyboard entries.      With   the   function   switch   in   an   operational mode, the MODE switch in SC, the frequency stored at a   particular   location   of   the   PRESET   switch   will   be displayed.    Changing  the  PRESET  switch  position  will automatically cause the new frequency corresponding to the new switch location to be displayed.  Frequency, or hopset    number    is    normally    visible    on    the    display. Depression  of  the  FREQ  button  on  the  keyboard  will display    the    current    operating    frequency    or    hopset number after such times.  The frequency offsets ( 5 or 10 kHz ) are operative in either MAN or a numbered preset  position  of  the  PRESET  switch.    These  offsets, once  applied,  will  be  displayed  as  the  true  operating frequency    when    FREQ    is    pressed.        Time    is    also available  for  display  in  any  operational  mode.    Time  is indicated  in  a  24-hour  system  by  days,  hours/minutes, and minutes/seconds.  CUE will also be displayed in an 3-14